The bug looks similar to Bug ID - 699119, so assigning to the concern owner.
@kojii -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

ClusterFuzz has detected this issue as fixed in range 476474:476505.

Detailed report: https://clusterfuzz.com/testcase?key=4545419486167040

Fuzzer: inferno_layout_test_unmodified
Job Type: linux_ubsan_vptr_content_shell_drt
Platform Id: linux

Crash Type: CHECK failure
Crash Address: 
Crash State:
  false in FontCache.cpp
  blink::FontCache::CrashWithFontInfo
  blink::FontFallbackIterator::Next
  
Sanitizer: undefined (UBSAN)

Regressed: https://clusterfuzz.com/revisions?job=linux_ubsan_vptr_content_shell_drt&range=457924:457941
Fixed: https://clusterfuzz.com/revisions?job=linux_ubsan_vptr_content_shell_drt&range=476474:476505

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=4545419486167040


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.